That was the word yesterday from scientists gathered for the annual meeting of the American Association for the Advancement of Science.

Smallscale studies in recent years have shown that adding iron to small patches of ocean triggers blooms of phytoplankton, singlecelled algae that absorb carbon from carbon dioxide in the atmosphere as they grow in the sunlit, upper ocean.

But those experiments say little about the impact on larger marine life, or what might happen to the entire food chain by seeding ocean water with tankerloads of iron particles.

understand a little bit about how iron fertilization works with microscopi cheap michael kors handbags sale c organisms on small scales, said Mike Landry, a researcher from the Scripps Institution of Oceanography in La Jolla. dont know how this scales up toward large organisms. scientists said that seeding the oceans with iron in one place could cheap michael kors handbags sale profoundly alter the food chain in other parts of the ocean.

Some studies even suggest that adding iron to the oceans could lead to the creation of nitrous oxide and methane, greenhouse gases that are more potent than carbon dioxide at trapping heat from the sun.

nitrous oxide that you create is worse than the C02 that you sequester, Sallie Chisholm, a researcher at the Massachusetts Institute of Technology, said of one study that estimated the outcome of seeding the oceans with iron over 100 years.

Scientists introduced the idea of the oceans with iron in 1990. But smallscale experiments in the Southern Ocean near Antarctica where currents keep the iron in a limited area have raised more questions than they have answered, scientists say.

Nevertheless, evidence suggesting that adding iron does increase phytoplankton has captured the imagination of policymakers and business people.

Finding ways to take carbon dioxide, a main byproduct of the burning of fossil fuels, out of the atmosphere and hiding it away either by burying it in the ground or placing it deep in the ocean has intrigued the federal Department of Energy as a option for dealing with rising greenhouse gases.

Increasing fuel efficiency, or turning to cleaner, carbonfree fuels such as nuclear, solar and wind power, may not be enough to stem the tide, according to an Energy Department briefing paper on the subject.

The oceans are attractive targets in part because they absorb so much of the carbon cycled between Earth and its atmosphere.

Phytoplankton, like terrestrial plants, convert carbon dioxide from the atmosphere into organic carbon during photosynthesis. Although they make up less than 1 percent of the Earths biomass, phytoplankton are responsible for roughly half of Earths natural carbon cycle.

The oceans are huge for carbon because when phytoplankton die, they sink deep into the oceans, carrying the carbon in their tissues with them out of circulation for long periods of time.

But adding iron to the oceans could change that system, scientists said. Boosting phytoplankton populations by fertilizing oceans could lead to more predation by zooplankton.

Zooplankton, in turn, are eaten by larger sea creatures whales among them that then release carbon dioxide back into the atmosphere as they breathe. Phytoplankton will never have enough time to die naturally and sink to the oceans interior, and the carbon they hold will be returned to the atmosphere as carbon dioxide, they said.

If the oceans end up taking in more carbon than they do now, that could lead to other problems. Oxygen from the carbon dioxide that oceans absorb will be consumed by bacteria, leading to an increase in methane, Chisholm said. Methane, eventually released into the atmosphere, is 22 times more potent than carbon dioxide as a greenhouse gas, she said.

certainly not the answer to our problem, Chisholm said of fertilizing the oceans with iron. is the problem: Were putting too much carbon dioxide into the atmosphere. cheap michael kors handbags sale